FIELD OF THE INVENTION
[0001] This invention relates to a heat-resistant resin composition. More particularly,
it relates to a resin composition suitable for a material of parts of electronic and
electrical equipment, which is excellent not only in heat resistance but also in impact
resistance as well as flame retardancy.
BACKGROUND OF THE INVENTION
[0002] Housings of electronic and electrical equipment, such as TV sets, CRT, various computers,
facsimiles, and word processors, are generally made of flame-retardant styrene resins,
e.g., acrylonitrile-butadiene-styrene terpolymers (ABS resins). These flame-retardant
styrene resins generally have a heat distortion temperature between 70 and 90°C at
the highest, as measured under a load of 264 psi according to ASTM D648, and the insufficiency
in heat resistance frequently causes troubles in some uses or sizes of the products.
[0003] Synthetic resins having a heat distortion temperature of 100°C or higher include
polyphenylene oxide resins (PPO) and polycarbonate resins (PC), but they are poor
in molding properties. It has been therefore demanded to develop synthetic resins
or resin compositions which are inexpensive and excellent in both heat resistance
and flame retardancy.
[0004] In order to improve molding properties of PPO and PC, it has been proposed to blend
PPO or PC with heat-resistant polymers, e.g., styrene-maleimide copolymers, as disclosed
in U.S. Patents 4,278,775 and 4,160,792. Although these polymer blends exhibit satisfactory
heat resistance and molding properties, there still remains the problem of poor flame
retardancy.
[0005] It has also been proposed to blend vinyl chloride resins with styrene-maleimide copolymers
as disclosed in U.S. Patent 4,458,046. This composition is, though excellent in flame
retardancy, poor in heat resistance.
[0006] It has further been proposed to add a halogen-containing flame retardant, e.g.,
decabromodiphenyl ether, to styrene-maleimide copolymers as described in U.S. Patent
4,032,509. The composition is, however, insufficient in flame retardancy and liable
to drip with fire, a so-called dripping.
[0007] It has furthermore been attempted to copolymerize a monomer, e.g., styrene compounds
and maleimide compounds, with a halogen-containing comonomer, such as brominated phenylmaleimide
compounds as disclosed in U.S. Patent 4,609,711 and 4,661,574, and brominated (meth)acrylate
compounds as disclosed in U.S. Patent 4,051,311. However, the copolymers should have
a large content of the expensive halogen-containing monomer so as to impart sufficient
flame retardancy, which is unacceptable for practical use.
[0008] Thus, it has been keenly demanded to develop a synthetic resin or a composition thereof
which satisfy all the requirements of flame retardancy, heat resistance, impact resistance,
and molding properties.
SUMMARY OF THE INVENTION
[0009] One object of this invention is to provide a resin composition free from the above-described
disadvantages, i.e., a resin composition which is excellent in heat resistance and
impact resistance, satisfactory in flame retardancy and molding properties, and also
relatively cheap.
[0010] The present invention relates to a resin composition comprising:
(A) at least one heat-resistant resin selected from the group consisting of (1) a
copolymer comprising a styrene compound and an α,β-unsaturated dicarboxylic acid imide
compound (hereinafter simply referred to as "imide compound") and (2) a rubber-reinforced
copolymer comprising a styrene compound and an imide compound,
(B) at least one thermoplastic resin selected from the group consisting of (1) a high-impact
resin obtained by graft-copolymerizing (i) styrene and acrylonitrile or (ii) styrene
and methyl methacrylate to (iii) a butadiene rubber, an ethylene-propylene rubber
or an acrylic ester rubber and (2) a copolymer resin comprising (i) styrene and acrylonitrile
or (ii) styrene and methyl methacrylate,
(C) an antimony oxide,
(D) at least one bromine-containing reaction product selected from the group consisting
of (1) a compound having a molecular weight of from 1,200 to 6,000 and a bromine content
of from 5.0 to 60% by weight, obtained by reacting a bromine-containing epoxy compound
and 1,3,5-tribromophenol, and (2) a compound obtained by reacting a bromine-containing
epoxy compound having an epoxy equivalent of from 450 to 7,000 and a bromine content
of from 5.0 to 52% by weight and an acrylonitrile-butadiene copolymer having a carboxyl
group at the both terminals thereof and a molecular weight of from 1,000 to 10,000,
and
(E) at least one silicon-containing compound selected from the group consisting of
(1) silicone oil, (2) a ladder silicone resin, and (3) an alkoxysilane having a mercapto
group, a vinyl group or a methacryloyl group,
wherein the amounts of the styrene compound and imide compound in said heat-resistant
resin (A) are from 10 to 50% by weight based on the total amount of said heat-resistant
resin (A) and thermoplastic resin (B), respectively; the ratio of the imide compound
to the total amount of said styrene compound and imide compound is from 5 to 50% by
weight; the total amount of a rubber reinforcement used in the rubber-reinforced copolymer
of said heat-resistant resin (A) and the butadiene rubber, ethylene-propylene rubber
and acrylic ester rubber used in said high-impact resin is from 5 to 35% by weight
based on the total amount of said heat-resistant resin (A) and thermoplastic resin
(B); the amount of said antimony oxide (C) is from 0.5 to 10 parts by weight per 100
parts by weight of the total amount of said heat-resistant resin (A) and thermoplastic
resin (B); the amount of said bromine-containing reaction product (D) is from 5.0
to 40 parts by weight per 100 parts by weight of the total amount of said heat-resistant
resin (A) and thermoplastic resin (B); and the amount of said silicon-containing compound
(E) is from 0.01 to 15 parts by weight per 100 parts by weight of the total amount
of said heat-resistant resin (A) and thermoplastic resin (B).
DETAILED DESCRIPTION OF THE INVENTION
(A) Heat Resistant Resin:
[0011] The heat-resistant resin which can be used in the present invention is selected from
the group consisting of (1) a copolymer comprising a styrene compound and an α,β-unsaturated
dicarboxylic acid imide compound [hereinafter referred to as heat-resistant resin
(1)], and (2) a rubber-reinforced copolymer comprising a styrene compound and an α,β-unsaturated
dicarboxylic acid imide compound [hereinafter referred to as heat-resistant resin
(2)].
[0012] The styrene compound to be used as a copolymerization component in the heat-resistant
resins (1) and (2) includes styrene and its derivatives including substituted styrenes
having on the benzene ring or on the α-carbon of the vinyl group one or more substituents
such as a halogen atom (e.g., F, Cl, Br and I) and a straight-chain, branched-chain
or alicyclic hydrocarbon group having up to 8 carbon atoms (e.g., methyl, ethyl, isopropyl,
n-octyl, cyclohexyl, etc.) which may also be substituted with a halogen atom. Example
of the styrene compound include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, 2,4-dimethyl styrene, 2,5-dimethylstyrene, 2,6-dimethylstyrene,
3,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene, 2,4,5-trimethylstyrene,
pentamethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,5-diethylstyrene,
3,5-diethylstyrene, 2,4,5-triethylstyrene, 2,3,4,5-tetraethylstyrene, pentaethylstyrene,
o-isopropylstyrene, m-isopropylstyrene, p-isopropylstyrene, p-n-butylstyrene, m-sec-butylstyrene,
p-sec-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene, p-hexylstyrene, p-heptylstyrene,
p-octylstyrene, p-sec-amylstyrene, p-sec-hexylstyrene, p-sec-heptylstyrene, p-sec-octylstyrene,
o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,3-dichlorostyrene, 2,4-dichlorostyrene,
2,5-dichlorostyrene, 2,6-dichlorostyrene, 3,4-dichlorostyrene, 3,5-dichlorostyrene,
2-chloro-5-methylstyrene, 4-chloro-3-methylstyrene, 2-chloro-3,4-dimethylstyrene,
2-chloro-3,5-dimethylstyrene, 4-chloro-2,5-dimethylstyrene, 2,3-dichloro-4,5-dimethylstyrene,
trichlorostyrene, 2,4,5-trichlorostyrene, 2,3,4-trichlorostyrene, tetrachlorostyrene,
pentachlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, 2,5-dibromostyrene,
3,4-dibromostyrene, 2,4,5-tribromostyrene, 2-bromo-5-methylstyrene, 4-bromo-3-methylstyrene,
p-(2-bromoethyl)styrene, o-iodostyrene, m-iodostyrene, p-iodostyrene, o-fluorostyrene,
m-fluorostyrene, p-fluorostyrene, 2,4-di fluorostyrene, 2,5-difluorostyrene, 4-fluoro-2,5-dichlorostyrene,
5-fluoro-2,4-dichlorostyrene, 2,5-difluoro-4-chlorostyrene, pentafluorostyrene, m-trifluoromethylstyrene,
2,5-di(trifluoromethyl)styrene, 2-bromo-4-trifluoromethylstyrene, 2-fluoro-3-trifluoromethylstyrene,
2,4,6-tris(trifluoromethyl)styrene, and p-trifluoromethylstyrene.
[0013] The imide compound includes those represented by formula (I):

wherein R₁, R₂, and R₃, which may be the same or different, each represents a hydrogen
atom or a hydrocarbon group having up to 12 carbon atom which may be straight-chain,
branched-chain, alicyclic or aromatic and which may be substituted with a halogen
atom.
[0014] Typical examples of the imide compound of formula (I) are maleimide, N-methylmaleimide,
N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide,
N-tert-butylmaleimide, N-hexylmaleimide, N-cyclohexylmaleimide, N-octylmaleimide,
N-decylmaleimide, N-dodecylmaleimide, N-benzylmaleimide, N-2-phenylethylmaleimide,
N-vinylmaleimide, N-phenylmaleimide, N-(o-tolyl)maleimide, N-(m-tolyl)maleimide,
N-(p-tolyl)maleimide, N-(o-ethylphenyl)maleimide, N-(m-ethylphenyl)maleimide, N-(p-ethylphenyl)maleimide,
N-(p-dodecylphenyl)maleimide, N-(o-vinylphenyl)maleimide, N-(m-vinylphenyl)maleimide,
N-(p-vinylphenyl)maleimide, N-(o-bisphenyl)maleimide, N-(p-bisphenyl)maleimide,
N-(o-chlorophenyl)maleimide, N-(p-chlorophenyl)maleimide, N-(o-bromophenyl)maleimide,
N-(m-bromophenyl)maleimide, N-(p-bromophenyl)maleimide, and N-laurylmaleimide.
[0015] The rubber which can be used as a reinforcement of the heat-resistant resin (2) preferably
has a Mooney viscosity (ML
l+4) of from 10 to 150 at 100°C and includes a styrene-butadiene copolymer rubber (the
styrene content is usually 40% by weight or less), a butadiene homopolymer rubber,
a hydrogenated styrene-butadiene copolymer rubber obtained by hydrogenation of the
above-described styrene-butadiene copolymer rubber, and an ethylene-propylene copolymer
rubber (the ethylene content is usually from 40 to 90% by weight and preferably from
55 to 85% by weight).
[0016] The heat-resistant resin (2) can be obtained by graft polymerization of the styrene
compound and imide compound to the rubber reinforcement. The rubber is usually used
in an amount of from 3 to 20 parts by weight, preferably from 5 to 15 parts by weight,
per 100 parts by weight of the heat-resistant resin (2).
[0017] Both the heat-resistant resins (1) and (2) can be prepared by commonly employed and
well-known processes such as aqueous suspension polymerization, emulsion polymerization,
solution polymerization, and bulk polymerization.
[0018] In either of the heat-resistant resins (1) and (2), the copolymerization ratio of
the imide compound to the total amount of the styrene compound and the imide compound
ranges from 5 to 30% by weight, preferably from 10 to 30% by weight, more preferably
from 10 to 25% by weight. If it is less than 5%, the resulting resin composition lacks
heat resistance. If it exceeds 50%, molding properties are seriously deteriorated.
[0019] The copolymer or copolymer component in the heat-resistant resins (1) or (2) may
further contain an unsaturated nitrile monomer, e.g., acrylonitrile and methacrylonitrile,
or methyl methacrylate usually at a copolymerization ratio of up to 30% by weight.
[0020] The heat-resistant resin as the component (A) may be a blend of the heat-resistant
resin (2) containing a relatively large proportion of the rubber reinforcement as
a master batch with the heat-resistant resin (1).
[0021] In the preparation of the heat-resistant resin (A), each of the styrene compound,
imide compound, and rubber reinforcement can be used either individually or in combinations
of two or more thereof.
(B) Thermoplastic Resin:
[0022] The thermoplastic resin which can be used in the present invention is selected from
the group consisting of (1) a high-impact resin obtained by graft copolymerizing
(i) styrene and acrylonitrile or (ii) styrene and methyl methacrylate to (iii) a rubber
selected from the group consisting of a butadiene rubber, an ethylenepropylene rubber
and an acrylic ester rubber, and (2) a copolymer of (i) styrene and acrylonitrile
or (ii) styrene and methyl methacrylate (hereinafter referred to as a styrene copolymer
resin).
(1) High-Impact Resin:
[0023] The rubber to be used in the preparation of the high-impact resins is selected from
butadiene rubbers including:
a butadiene homopolymer rubber and a random or block copolymer rubber comprising butadiene
and a small amount (usually 40% by weight or less) of styrene or acrylonitrile;
ethylene-propylene rubbers including a copolymer rubber consisting of ethylene and
propylene, and a copolymer rubber consisting of ethylene, propylene, and a small amount
(usually 10% by weight or less) of (i) a straight-chain or branched diolefin having
the two double bonds in the terminals thereof and preferably having up to 18 carbon
atoms (e.g., 1,4-pentadiene, 3-ethyl-1,4-pentadiene, 3-ethyl-3-methyl-1,4-pentadiene,
2,4-dimethyl-1,4-pentadiene, 3,3-dimethyl-1,4-pentadiene, 1H,3H-hexachloro-1,4-pentadiene,
3-isopropyl-2-methyl-1,4-pentadiene, 3-methoxy-1,4-pentadiene, 2-methyl-1,4-pentadiene,
3-methylene-1,4-pentadiene, 1,5-hexadiene, 3-ethyl-2-methyl-1,5-hexadiene, 1,6-heptadiene,
1,7-octadiene and 4,5-diethyl-4,5-dimethyl-1,7-octadiene), (ii) a straight-chain
or branched diolefin having one of the double bonds in the terminals thereof and preferably
having up to 18 carbon atoms (e.g., 1,4-hexadiene, 1,3-hexadiene, 2-ethyl-1,3-hexadiene,
4-ethyl-1,3-hexadiene, 2-ethyl-3,4-dimethyl-1,3-hexadiene, 2-ethyl-4-methyl-1,3-hexadiene,
2,3,5,5-tetramethyl-1,3-hexadiene, 2,4,5,5-tetramethyl-1,3-hexadiene, 2,3,4-trimethyl-1,3-hexadiene,
2,5,5-trimethyl-1,3-hexadiene, 1,4-hexadiene, 4-ethyl-1,4-hexadiene, 5-methyl-1,4-hexadiene,
1,3-heptadiene, 2-ethyl-1,3-heptadiene, 3-ethyl-1,3- heptadiene, 2-methyl-1,3-heptadiene,
6-methyl-1,3-heptadiene, 2-propyl-1,3-heptadiene, 2,3,6-trimethyl-1,3-heptadiene,
3,5,5-trimethyl-1,3-heptadiene, 1,4-heptadiene, 4-propyl-1,4-heptadiene, 1,5-heptadiene,
4-butyl-1,5-heptadiene, 4-butyl-4-methyl-1,5-heptadiene, 2,4-dimethyl-1,5-heptadiene,
2,6-dimethyl-1,5-heptadiene, 3,4-dimethyl-1,5-heptadiene, 3,6-dimethyl-1,5-heptadiene,
2-methyl-1,5-heptadiene, 3-methyl-1,5-heptadiene, 1,2-octadiene, 1,3-octadiene, 2-methyl-1,3-octadiene,
4-methyl-1,3-octadiene, 1,4-octadiene, 3-ethyl-1,4-octadiene, 5-methyl-1,5-octadiene,
4,5,6-trimethyl-1,5-octadiene, 1,6-octadiene, 3,7-dimethyl-1,6-octadiene, 3,7-dimethyl-3-pentyloxy-1,6-octadiene
and 3-heptyloxy-3,7-dimethyl-1,6-octadiene) or (iii) bicyclo[2.2.1]heptene-2 or a
derivative thereof (e.g., 5-methylbicyclo[2.2.1]heptene-2, 5,6-trimethylenebicyclo[2.2.1]heptene-2
(exo-form and endo-form), 5-methylenebicyclo[2.2.1]heptene-2 and bicyclo[2.2.1]-hepta-2,5-diene(2,5-norbornadiene)
dicyclopentadiene (exo-form and endo-form)); and
acrylic ester rubbers including a homopolymer of an acrylic ester such as alkyl acrylates
and alkoxyalkyl acrylates (e.g., methyl acrylate, ethyl acrylate, propyl acrylate,
butyl acrylate, pentyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate,
nonyl acrylate, decyl acrylate, dodecyl acrylate, cyanoethyl acrylate, methoxyethyl
acrylate, ethoxyethyl acrylate, butoxyethyl acrylate and ethoxypropyl acrylate) and
a copolymer consisting of an acrylic ester and a small amount (usually 10% by weight
of less) of other monomers such as helogen-containing unsaturated compounds (e.g.,
vinyl chloroacetate, chloroethyl vinyl ether and allyl chloroacetate), epoxy group-containing
unsaturated compounds (e.g., glycidyl acrylate, glycidyl methacrylate, vinyl glycidyl
ether, allyl glycidyl ether and methallyl glycidyl ether), amino group-containing
esters of unsaturated carboxylic acids (e.g., dimethylaminoethyl methacrylate, diethylaminoethyl
methacrylate and dimethylaminoethyl acrylate), amino group-containing amides of unsaturated
carboxylic acids (e.g., N-(4-anilinophenyl)acrylamide and N-(anilinophenyl)methacrylamide),
and vinyl monomers (e.g., styrene, vinyltoluene, α-methylstyrene, acrylonitrile, methacrylonitrile,
cyclohexyl acrylate and cyclohexyl methacrylate).
[0024] The rubber to be used in the preparation of the high-impact resins preferably has
a Mooney viscosity of from 20 to 140, more preferably from 30 to 120, though it varies
depending on the kind. These rubbers are widely produced in industry and utilized
in various fields. The processes for preparing them and characteristics and utility
thereof are well known in the art [cf. Shu Kanbara,
Gosei Gomu Handbook, Asakura Shoten (1967)].
[0025] The graft polymerization for the preparation of the high-impact resins can be carried
out according to bulk polymerization, solution polymerization, emulsion polymerization,
aqueous suspension polymerization, and a combination thereof (e.g., bulk polymerization
followed by aqueous suspension polymerization). The rubber is usually used in an amount
of from 3 to 40 parts, preferably from 5 to 35 parts, more preferably from 5 to 30
parts, by weight per 100 parts by weight of the resulting high-impact resin. The high-impact
resin may be obtained by preparing a graft polymer having a high rubber content by
using a relatively large amount of the rubber and then mixing the graft polymer with
a homo- or copolymer of styrene, acrylonitrile and methyl methacrylate. In this case,
the above-recited amount of the rubber is calculated based on the total amount of
the blend. The monomers bonded to the rubbery polymer as a grafted side chain (i.e.,
styrene and acrylonitrile or methyl methacrylate) has a molecular weight of from 1,000
to 300,000, preferably from 2,000 to 200,000. It is generally rare that the graft
monomers are completely bonded to the rubbery polymer. The reaction system contains
both the grafted polymer and a homo- or copolymer of the monomers remaining unbound
to the rubbery polymer. This mixture is used as such without separating the free homo-
or copolymer.
[0026] Typical examples of the thus prepared high-impact resins include an acrylonitrile-butadiene-styrene
terpolymer (ABS resin) obtained by graft polymerization of styrene and acrylonitrile
to a butadiene homopolymer rubber, a styrene-butadiene block or random copolymer rubber
(SBR) or an acrylonitrile-butadiene copolymer rubber (NBR); a methyl methacrylate-butadiene
styrene terpolymer (MBS resin) obtained by graft polymerization of styrene and methyl
methacrylate to a butadiene homopolymer rubber or SBR; an acrylonitrile-acrylic ester-styrene
terpolymer (AAS resin) obtained by graft polymerization of acrylonitrile and styrene
to an acrylic ester rubber; and a graft copolymer resin (AES resin) obtained by graft
polymerization of acrylonitrile and styrene to an ethylene-propylene copolymer rubber.
[0027] In the preparation of the high-impact resin, it is possible that styrene and acrylonitrile
or methyl methacrylate may be graft polymerized to a relatively large amount (usually
40 to 70% by weight) of the rubber in the same manner as described above to obtain
a high-impact resin having a high rubber content (e.g., an acrylonitrile-butadiene-styrene
terpolymer resin having a high rubber content) and mixing the graft copolymer with
the above-described heat-resistant resin or the styrene copolymer resin hereinafter
described so as to have a composition as specified in the present invention.
[0028] The above-described high-impact resins are currently produced on an industrial scale
and utilized in various fields, and the processes for preparing them are well known
in the art.
(2) Styrene Copolymer Resin:
[0029] The styrene copolymer resin as the thermoplastic resin (B) includes a styrene-acrylonitrile
copolymer resin (AS resin) and a styrene-methyl methacrylate copolymer resin (MS resin).
These styrene copolymer resins generally have a styrene content of from 40 to 85%
by weight, preferably from 50 to 80% by weight.
[0030] The styrene copolymers can be industrially produced in the same polymerization process
as the above-described graft polymerization, and are currently utilized in various
fields.
(C) Antimony Oxide:
[0031] The antimony oxide which can be used in the present invention is widely employed
as a flame retarding aid for bromine-containing compounds, and includes antimony trioxide
and antimony pentoxide. The antimony oxide has an average particle size of from 1
to 150 µm.
(D) Bromine-Containing Reaction Product:
[0032] The bromine-containing reaction product which can be used in the present invention
is selected from (1) a bromine-containing compound having a molecular weight of from
1,200 to 6,000 and a bromine content of from 5.0 to 60% by weight, which is obtained
by reacting a bromine-containing epoxy compound (1) and 1,3,5-tribromophenol [hereinafter
referred to as bromine-containing compound (1)], and (2) a reaction product obtained
by reacting a bromine-containing epoxy compound (2) having an epoxy equivalent of
from 450 to 7,000 and a bromine content of from 5.0 to 52% by weight and an acrylonitrile-butadiene
copolymer having a carboxyl group at the both terminals thereof and having a molecular
weight of from 1,000 to 10,000 [hereinafter referred to as bromine-containing compound
(2)].
[0033] Typically included in the bromine-containing compound (1) are those obtained by reacting
a bromine-containing epoxy compound (1) represented by formula (II):

wherein R₄ and R₅, whi.ch may be the same or different, each represents a hydrogen
atom or a methyl group; m represents 0 or an integer of from 1 to 7; and i₁ to i₄
each represents 0 or an integer of from 1 to 4, provided that i₁ to i₄ are not 0 at
the same time, with 1,3,5-tribromophenol, the main component of which is represented
by formula (III):

wherein R⁵, m, and i₁ to i₄ are as defined above.
[0034] As a result of the reaction, the terminal epoxy groups of the compound of formula
(II) are reacted, with the proportion of the unreacted epoxy groups and thus remaining
in the product being 15% at the most based on the initial epoxy content.
[0035] In formulae (II) and (III), i₁ to i₄ each is preferably 1 to 4.
[0036] The bromine-containing epoxy compound (1) represented by formula (II) can be prepared
by reacting 4,4′-dioxydiphenylpropane (bisphenol A) containing at least one bromine
atom with epichlorohydrin according to a conventional process for preparing ether
type epoxy resins. It can also be prepared by brominating an ether type epoxy resin
containing no bromine.
[0037] The bromine-containing compound (1) has a molecular weight of from 1,200 to 6,000,
preferably from 1,400 to 5,000, and a bromine content of from 5.0 to 60% by weight,
preferably from 10 to 60% weight.
[0038] The bromine-containing compound (2) can be obtained by reacting a bromine-containing
epoxy compound (2) having an epoxy equivalent of from 450 to 7,000 and a bromine content
of from 5.0 to 52% by weight with an acrylonitrile-butadiene copolymer having a carboxyl
group at the both terminals thereof and having a molecular weight of from 1,000 to
10,000.
[0039] The bromine-containing epoxy compound (2) has a bromine content of from 5.0 to 52%
by weight, preferably from 7.0 to 52% by weight, more preferably from 10 to 52% by
weight. If the bromine content of the epoxy compound (2) is less than 5.0% by weight,
the resulting resin composition exhibits insufficient flame retardancy. The bromine-containing
epoxy compound (2) has an epoxy equivalent of from 450 to 7,000, preferably from 450
to 6,000, more preferably from 500 to 5,000. If the epoxy equivalent is less than
450, the resin composition exhibits poor heat resistance. On the other hand, if the
epoxy equivalent exceeds 7,000, the bromine- containing compound (2) is poor in compatibility
with other components, resulting in reduced surface gloss of molded articles of the
composition.
[0040] The bromine-containing epoxy compound (2) includes those represented by formula (IV):

wherein R₄ and R₅ are as defined above; m′ represents 0 or an integer of from 1 to
30; and i₁′ to i₄′ each represents an integer of from 1 to 4.
[0041] The bromine-containing epoxy compound (2) can be obtained by reacting 4,4′-dioxydiphenylpropane
(bis-phenol A) containing at least one bromine atom with epichlorohydrin according
to a known process for preparing ether type epoxy resins. In can also be obtained
by reacting an ether type epoxy resin containing no bromine with bromine.
[0042] The acrylonitrile-butadiene copolymer having a carboxyl group at the both terminals
thereof has a molecular weight of from 1,000 to 10,000, preferably from 1,500 to 8,000,
more preferably from 2,000 to 7,000. If the molecular weight is less than 1,000, the
resulting resin composition has insufficient impact resistance. An acrylonitrile-butadiene
copolymer having a molecular weight exceeding 10,000 lacks compatibility with the
above-described bromine-containing epoxy compound. The acrylonitrile-butadiene copolymer
has an acrylonitile content of 40% by weight or less. If the acrylonitrile content
exceeds 40%, the copolymer would have a markedly increased viscosity, resulting in
difficulty on handling.
[0043] In the preparation of the bromine-containing compound (2), the reaction between the
bromine-containing epoxy compound (2) and the acrylonitrile-butadiene copolymer
having a carboxyl group at the both terminals can be carried out either by heating
them in a high temperature or by heating them in the presence of an amine catalyst
with or without a solvent.
[0044] The amount of the acrylonitrile-butadiene copolymer having a carboxyl group at the
both terminals to be reacted usually ranges from 5.0 to 100 parts by weight, preferably
from 5.0 to 80 parts by weight, per 100 parts by weight of the bromine-containing
epoxy compound (2). If it is less than 5.0 parts, sufficient effects to improve impact
resistance cannot be produced. If it exceeds 100 parts, the resulting resin composition
lacks heat resistance.
(E) Silicon-Containing Compound:
[0045] The silicon-containing compound which can be used in the present invention is selected
from the group consisting of a silicone oil, a ladder silicone resin, and an alkoxysilane
having a mercapto group, a vinyl group or a methacryloyl group.
[0046] The silicone oil to be used has a viscosity usually of from 10 to 100,000 cps, preferably
from 50 to 50,000 cps, more preferably from 50 to 20,000 cps, at 25°C. Silicone oils
having a viscosity less than 10 cps (at 25°C) tend to vaporize during keaning. Silicone
oils having a viscosity exceeding 10,000 cps (at 25°C) are poor in compatibility.
[0047] Typical examples of such silicone oils include polydimethylsiloxane, polymethylphenylsiloxane,
and polymethylhydrogensiloxane. In addition, modified silicone oils obtained by substituting
the alkyl group of polydialkylsiloxanes (usually having from 1 to 18 carbon atoms
in their alkyl moiety) with epoxy, amino, carboxyl, or alcohol.
[0048] The ladder silicone resins can be represented by formula (V):

wherein R₆ and R₇, which may be the same or different, each represents a straight-chain
alkyl group having from 1 to 4 carbon atoms, a phenyl group, a hydroxyl group, a carboxyl
group or an aminoalkyl group having from 1 to 4 carbon atoms, the total number of
the hydroxyl, carboxyl and aminoalkyl groups being not more than 10 mol% based on
the number of the groups for R₆ and R₇; and n represents an integer of from 10 to
100.
[0049] The ladder silicone resin may be used in the resin composition either as such or
after being preliminarily condensed by heating at 80 to 300°C for 5 minutes to 1 hour.
[0050] The alkoxysilane compound to be used is an alkoxysilane having a functional group
selected from the group consisting of a mercapto group, a vinyl group, and a methacryloyl
group. Typical examples of the alkoxy silane compound include those represented by
formula (VI):

wherein R and R′, which may be the same or different, each represents a straight-chain
or branched alkyl group having from 1 to 6 carbon atoms; Y represents a vinyl group
(CH₂=CH-), a mercaptoalkyl group represented by formula HS-R₈-, wherein R₈ represents
a straight-chain or branched alkylene group having from 1 to 6 carbon atoms, or a
methacryloylalkyl group represented by formula

wherein R₉ represents a straight chain or branched alkylene group having from 1 to
6 carbon atoms; and x represents 2 or 3.
[0051] Specific examples of the alkoxysilane compound of formula (VI) are γ-mercaptopropylmethyldimethoxysilane,
Y-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane,
γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane,
Ymethacryloyloxypropyltripropoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane,
γ-methacryloyloxypropylmethyldipropoxy silane, γ-methacryloyloxypropyltriisopropoxysilane
and γ-methacryloyloxypropylmethyldiisopropoxysilane.
[0052] The silicon-containing compound (E) reacts with the above-described heat-resistant
resin or thermoplastic resin on heating at high temperatures to form an Si-C bond,
thereby to prevent the resulting resin composition from dripping.
[0053] The silicon-containing compound (E) produces great effects on improvement of flame
retardancy and particularly antidripping properties. Such effects become especially
conspicuous in a combined use with the above-described bromine-containing reaction
product (D).
[0054] The amounts of the styrene compound and imide compound in the heat-resistant resins
(1) and/or (2) range from 10 to 50% by weight, respectively , based on the total amount
of the heat-resistant resin (A) and thermoplastic resin (B) (hereinafter collectively
referred to as "high polymers"). If it is outside the above range, the resulting resin
composition does not exhibit good heat resistance and good processability at the same
time.
[0055] The total amount of the rubber reinforcement used in the preparation of the heat-resistant
resin (2) and the rubber used in the preparation of the high-impact resin (i.e.,
butadiene rubbers, ethylene propylene rubbers and acrylic ester rubbers) (hereinafter
collectivelly referred to as "rubber components") ranges from 5 to 35% by weight,
preferably from 5 to 30% by weight, more preferably from 5 to 25% by weight, based
on the total amount of the high polymers. If the content of the rubber components
in the high polymers is less than 5%, the resulting composition lacks impact resistance.
If it exceeds 35%, the composition suffers reduction not only in molding properties
but also in heat resistance.
[0056] The amount of the antimony oxide ranges from 0.5 to 10 parts by weight per 100 parts
by weight of the high polymers. If it exceeds 10 parts, the resulting composition
shows reduced mechanical strength.
[0057] A combined use of the antimony oxide and the bromine-containing reaction product
synergistically brings about an improvement on flame retardancy. Manifestation of
such a synergistic effect requires use of the antimony oxide in an amount of at least
0.5 part, particularly from 1.0 to 8.0 parts, by weight per 100 parts by weight of
the high polymers.
[0058] The amount of the bromine-containing reaction product ranges from 5.0 to 40 parts
by weight, preferably from 5.0 to 35 parts by weight, per 100 parts by weight of the
high polymers. If it is less than 5.0 parts, the resulting resin composition fails
to exhibit sufficient flame retardancy. Use of the bromine containing reaction product
in amounts exceeding 40 parts not only increases the cost incurred but also results
in insufficiency of impact resistance.
[0059] It is preferable to use from 1 to 5 parts by weight of the bromine-containing reaction
product per part by weight of the antimony oxide.
[0060] The amount of the silicon-containing compound to be used varies depending on the
kind but usually ranges from 0.01 to 15 parts by weight per 100 parts by weight of
the high polymers.
[0061] In more detail, in case of the silicone oil, it is preferably used in an amount of
from 0.1 to 3.0 parts, more preferably from 0.1 to 2.5 parts, by weight per 100 parts
by weight of the high polymers. If the amount of the silicone oil is less than 0.1
part, the effect of drip prevention cannot be fully enjoyed. Use of more than 3.0
parts of the silicone oil tends to cause slippage during preparation of the composition
and also to reduce heat resistance of the composition.
[0062] In the case of the ladder silicone resin, it is preferably used in an amount of from
0.01 to 15 parts, more preferably from 0.1 to 2.5 parts, by weight per 100 parts by
weight of the high polymers. If its amount is less than 0.01 part, the effect of drip
prevention is insufficient. Use of more than 15 parts of the ladder silicone resin
deteriorates compatibility with the high polymers to reduce mechanical strength of
the resulting products.
[0063] In the case of the alkoxysilane compound, it is preferably used in an amount of from
0.1 to 5.0 parts, more preferably from 0.2 to 2.5 parts, by weight per 100 parts by
weight of the high polymers. If its amount is less than 0.1 part, the effect of drip
prevention is insufficient. Use of more than 5.0 parts may cause gelation.
[0064] The resin composition of the present invention can be prepared by uniformly mixing
the high polymers [i.e., the heat-resistant resin (A) and the thermoplastic resin
(B)], antimony oxide (C), bromine-containing reaction product (D), and silicon-containing
compound (E). If desired, the composition may further contain additives widely employed
in the field of the above-described high polymers according to the end use, such as
stabilizers to heat, oxygen and light, fillers, coloring materials, lubricants, plasticizers,
and antistatic agents, as long as the purposed characteristics of the composition
are not essentially impaired.
[0065] In carrying out mixing of the components, all the components may be mixed simultaneously,
or part of the components may be mixed in advance and the rest of the components are
mixed therewith. The mixing can be carried out by dry blending be the use of a mixing
machine commonly employed in the art, e.g., a Henschel mixer; or melt kneading by
the use of an open roll, an extruder, a kneader, a Banbury mixer, etc. In order to
ensure uniformity of the composition, two or more of these mixing modes can be combined.
For example, dry blending may be followed by melt kneading. In any case of combining
two or more of the dry blending modes or melt kneading modes, it is preferable that
the resulting resin mixture be pelletized by means of a pelletizer for use in the
subsequent molding step.
[0066] When the components are mixed by melt kneading or when the composition is molded
by the molding methods hereinafter described, such should be effected at a temperature
at which the high polymers used are melted. It should be noted, however, that the
melt kneading temperautre or molding temperature must be 280°C or lower since the
high polymers would undergo thermal decomposition or deterioration, or the bromine-containing
reaction product would undergo decomposition at higher temperatures.
[0067] The composition of the present invention can be molded into any desired shape by
various molding methods generally applied in the art, such as injection molding, extrusion
molding, compression molding, and blow molding. Further, the composition may be once
molded into sheet by the use of an extrusion molding apparatus and then formed into
a desired shape by vacuum forming, pressure forming or the like forming technique.
[0068] The present invention is now illustrated in greater detail by way of the following
Examples and Comparative Examples, but it should be understood that the present invention
is not deemed to be limited thereto.
[0069] In these examples, physical properties of the compositions were measured or evaluated
as follows.
1) Melt Flow Index (MI):
Measured at 250°C under a load of 5 kg in accordance with ASTM D1238.
2) Tensile Yield Strength:
Dumbbell specimens (ASTM No. 1) were used. Measured at a strain rate of 5 mm/min in
accordance with ASTM D638.
3) Izod Impact Strength:
Measured on notched specimens at 23°C in accordance with ASTM D256.
4) Heat Resistance:
Changes of samples on standing on a press at 250°C for 60 minutes were observed in
accordance with ASTM D648.
5) Flame Retardancy:
1.6 mm (1/16 in)-thick specimens were used subjected to frame retardancy test in accordance
with UL94.
[0070] The kinds and physical properties of the components used in the examples and processes
for preparing them are described below.
(A) Heat-Resistant Resin:
[0071] (a) In a 10 ℓ autoclave were charged 6,000 g of water, 2,400 g of styrene (ST), 800
g of acrylonitrile (AN), and 800 g of N-phenylmaleimide (N-PMI). In the autoclave
were further put 8 g of lauryl peroxide and 9.6 g of t-butyl peroxylaurate as initiators,
8 g of t-dodecylmercaptan as a chain transfer agent, and 20 g of calcium tertiary
phosphate and 0.3 g of sodium dodecylbenzenesulfonate as suspension stabilizers.
The mixture was heated at 80°C for 2 hours while stirring to effect polymerization.
The temperature of the system was raised to 120°C, at which the polymerization was
further continued for an additional period of 3 hours, followed by allowing to cool
to room temperature. There was obtained about 3,500 g of a pale yellow powder. This
product is hereinafter designated as heat-resistant resin (a).
[0072] Infrared absorption analysis (solution method) revealed that the powder is a terpolymer
consisting of ST, AN, and N-PMI at a weight ratio of 60:20:20. The heat-resistant
resin (a) had an intrinsic viscosity [η] of 0.950 (as measured at 30°C in chloroform
in a concentration of 0.05 g/50 ml, hereinafter the same) and a heat distortion temperature
of 118°C (as measured under a load of 264 psi according to ASTM D648 hereinafter the
same).
[0073] (b) To a monomer mixture of 2,400 g of ST, 800 g of AN, and 800 g of N-PMI was added
280 g of a butadiene homopolymer rubber having a Mooney viscosity of 35 ML
1+4, 100°C) and completely dissolved therein. The mixture was allowed to polymerize at
110°C for 2.5 hours. The resulting mixture containing the prepolymer produced was
added to 6,000 g of water containing the same amounts of the same initiator, chain
transfer agent and suspension stabilizer as used in the preparation of the heat-resistant
resin (a) to effect aqueous suspension polymerization at 80°C for 2 hours. The temperature
of the polymerization system was raised to 120°C, at which the aqueous suspension
polymerization was continued for an additional period of 3 hours, followed by allowing
to cool to room temperature. There was obtained about 3,300 g of a yellow powder.
[0074] The powder was analyzed in the same manner as for the heat-resistant resin (a) and,
as a result, found to be a graft polymer in which the monomers were grafted to the
butadiene homopolymer rubber at the same monomer unit weight ratio as in the heat-resistant
resin (a). This powder was designated as heat-resistant resin (b). The heat-resistant
resin (b) had an intrinsic viscosity [η] of 0.850 and a heat distortion temperature
of 108°C.
(B) Thermoplastic Resin:
(a) High-Impact Resin:
[0075] An acrylonitrile-butadiene-styrene terpolymer (ABS), a methyl methacrylate-butadiene-styrene
terpolymer (MBS), an acrylonitrile-acrylic ester rubber-styrene copolymer (AAS),
and an acrylonitrile-olefin rubber(ethylene-propylene rubber)-styrene copolymer (AES)
were prepared in the same manner as for the ABS resin, MBS rein, AAS resin, and AES
resin as used in the Examples and Comparative Examples of JP-A-58-134144 (the term
"JP-A" means an "unexamined published Japanese patent application").
(b) Styrene Copolymer Resin:
[0076] An acrylonitrile-styrene copolymer having an acrylonitrile content of 23% by weight
and an average degree of polymerization of about 750 (hereinafter abbreviated as "AS")
and a methyl methacrylate-styrene copolymer having a methyl methacrylate content of
25% by weight and an average degree of polymerization of about 800 (hereinafter abbreviated
as "MS") were used.
(C) Antimony Oxide:
[0077] Antimony trioxide (Sb₂O₃) was used.
(D) Bromine-Containing Reaction Product:
(a) Bromine-Containing Compound (1):
[0078] A bromine-containing reaction product of formula (III) wherein R₄ is a hydrogen atom
and R₅ is a methyl group, having an average molecular weight of about 2,000 and a
bromine content of 56% by weight [hereinafter referred to as "bromine-containing compound
(A)"] and a bromine-containlng reaction product which is the same as the bromine-containing
compound (A) except for having a bromine content of 55% by weight and an average molecular
weight of about 3,600 [hereinafter referred to as "bromine-containing compound (B)"]
were used.
(b) Bromine-Containing Compound (2):
[0079] A thousand grams of a bromine-containing epoxy compound represented by formula (IV)
wherein R₄ is a hydrogen and R₅ is a methyl group, having a bromine content of 52%
by weight and an average epoxy equivalent of 1,500, and 200 g of an acrylonitrile-butadiene
copolymer having an acrylonitrile content of 17% by weight and an average molecular
weight of 3,500 and having a carboxyl group at the both terminals thereof were uniformly
dissolved in 2,000 g of cellosolve acetate while stirring. To the mixed solution was
added 0.5 g of imidazole, and the temperature was elevated to 150°C to effect reaction
for 4 hours while stirring. The solvent was removed from the reaction solution by
evaporation, and the residue was dried in vacuo to obtain 1,150 g of a pale brown
powder [hereinafter referred to as "bromine-containing compound (C)"].
[0080] For comparison, decabromobiphenyl ether [hereinafter referred to as "bromine-containing
compound (D)"] and the same bromine-containing epoxy compound as used in the preparation
of the bromine-containing compound (C) [hereinafter referred to as "bromine-containing
compound (E)"] were used.
(E) Silicon-Containing Compound:
(a) Silicone Oil:
[0081] Polydimethylsilicone oil having a viscosity of 5,000 cps (as measured at 25°C, hereinafter
the same) [hereinafter referred to as "Si(1)"], polymethylphenyl silicone oil having
a viscosity of 1,000 cps [hereinafter referred to as "Si(2)"], polymethylhydrogensilicone
oil having a viscosity of 1,000 cps [hereinafter referred to as "Si(3)"], epoxysilicone
oil having a viscosity of 1,000 cps [hereinafter referred to as "Si(4)"], and aminosilicone
oil having a viscosity of 600 cps [hereinafter referred to as "Si(5)"] were used.
(b) Ladder Silicone Resin:
[0082] A ladder silicone resin represented by formula (V) wherein R₆ and R₇ each represents
a methyl group having a molecular weight of about 4,000 [hereinafter referred to as
"Si resin (1)"], a silicone resin of formula (V) wherein R₆ and R₇ each represents
a methyl group or a phenyl group with the methyl to phenyl molar ratio being 1:1 and
having a molecular weight of about 3,500 [hereinafter referred to as "Si resin (2)"],
and a silicone resin of formula (V) wherein R₆ and R₇ each represents a phenyl group
having a molecular weight of about 3,000 [hereinafter referred to as "Si resin (3)"]
were used. Each of these silicone resins was heated at 150°C for 30 minutes and ground,
and the undersize of a 200 mesh was used.
(c) Alkoxysilane Compound:
[0083] Vinyltrimethoxysilane [hereinafter referred to as "silane (1)"], γ-mercaptopropyltrimethoxysilane
[hereinafter referred to as "silane (2)"], γ-mercaptopropylmethyldimethoxysilane
[hereinafter referred to as "silane (3)"], and γ-methacryloyloxypropyltrimethoxysilane
[hereinafter referred to as "silane (4)"] were used.
EXAMPLES 1 TO 11 AND COMPARATIVE EXAMPLES 1 TO 4
[0084] The heat-resistant resin, thermoplastic resin, bromine containing compound, and silicone-containing
compound, the amount and the kind of which are indicated in Table 1, Sb₂O₃ (antimony
oxide) of the amount indicated in Table 1, and, as a stabilizer, 0.2 part by weight
of 2,6-di-t-butyl-p-cresol were dry blended in a Henschel mixer for 5 minutes. The
resulting mixture was kneaded and pelletized by means of a vented twin-screw extruder
(diameter: 30 mm). The temperature was set at 200°C at the cylinder 1, 220°C at the
cylinder 2, 240°C at the cylinder 3, 240°C at the adaptor, and 230°C at the die.
[0086] It is apparent from the results of Table 2 that the resin compositions according
to the present invention are excellent in not only flame retardancy and impact resistance
but also heat resistance.
[0087] According to the present invention, a combined use of the bromine-containing reaction
product and the silicon-containing compound provides a resin composition having well-balanced
physical properties. Such a combination also brings about improvements on flame retardancy
and particularly antidripping properties.
[0088] In addition to the superiority in flame retardancy, impact resistance and heat resistance,
the resin composition of the present invention is further characterized by its excellent
molding properties (i.e., fluidity) and capability of providing molding articles having
satisfactory gloss, excellent weather resistance, and freedom from color change.
[0089] Because of these excellent characteristics, the resin composition of the present
invention can be used in a broad range of application, such as TV cabinets, housings
of facsimiles, word processors, microcomputers, printers, etc., parts of various fire
alarms, and housings of applicances.
[0090] While the invention has been described in detail and with reference to specific embodiments
thereof, it will be apparent to one skilled in the art that various changes and modifications
can be made therein without departing from the spirit and scope thereof.